Automatic center-punch.



C. L. THROCKMORTON.

AUTOMATiC CENTER PUNCH.

APPLxcATloN man sEPT.23,19i4.

L22@ 193 n Patented May 8, 1917.

IH! NURRIS PETERS C0 FNOTD-LVYNO WASNINGIUN.D r

CHARLES L. THROCKMORTON,IOF SAN FRANCISCO, CALIFORNIA.

AUTOMATIC CENTER-PUNCH.

Specification of Letters Patent.

Patented May 8, 1917.

Application led September 23, 1914. Serial No. 863,988.

T0 all whom t may concern:

Be it known that I, CHARLES L. THROCK- MoR'roN, a citizen of the UnitedStates, residing in the city and county of San Francisco and State ofCalifornia, have invented new and useful Improvements in AutomaticCenter-Punches, of which the following is a specication.

My invention relates to an automatic center punch, wherein afrusto-conical member slidably mounted upon and concentric with a centerpunch operates in conjunction with a plurality of levers, pivotallymounted equidistant from the center of the said punch; and the objectsof my invention are, first, to provide improved means for automaticallyalining a center punch with the center of a shaft; and second, toprovide means for producing an indenture in the center of a cylindricalshaft.

I accomplish these features by means of the device disclosed in thedrawings forming a part of the present specification, wherein likecharacters of reference are used to designate similar parts throughoutthe said specification and drawings, and in which- Figure 1 is alongitudinal sectional view of the device disclosing the parts in anormal position.

Fig. 2 is a longitudinal sectional view disclosing the device centeredon a fragment of a shaft.

Fig. 3 is an end view of the device disclosing the disk for retainingthe movable levers in alinement. p

Referring to the drawings, the numeral 1 is used to designate a tubularmember having a disk 2 rigidly secured to one end thereof and at rightangles thereto, said disk being provided with a series of radial slots3.

Slidably mounted within the tubular member 1 is a center punch 4 havinga pin 5 therein arranged to engage slots 6 of the tubular member 1 forthe purpose of limiting the movement of the said center punch 4 withinthe tubular member 1.

A series of levers 7, which are preferably four in number, are pivotallysecured to the tubular member 1, as at 8, said pivotal points 8 beingequidistant from the longitudinal center of the center punch 4. Theouter ends of the levers 7 extend through the slots 3 of the disk 2,while the inner ends 9 of the levers 7 arel arranged to be engaged by afrusto-conical portion 10 of a handle 12, which is slidably mounted uponthe tubular member 1.

A collar 14 is secured to the tubular member 1 and a spring 15 isinterposed between said collar 14 and a shoulder 16 in the end of thehandle 12 so that the tension of the said spring 15 will normally retainthe outer end of the handle 12 against an annular flange 17 on theopposite end of the tubular member 1, to which the disk 2 is secured.

Inasmuch as the handle 12 and the frustoconical portion 10 thereon areconcentric with the tubular member l and the center punch 4, slidablymounted therein, it is obvious that the outer ends of the levers 7 willbe moved inward simultaneously and an equal distance when the saidfrusto-conical portion 10 is moved under the short ends 9 of the saidlevers 7.

It is also obvious that the outer ends of the said levers 7 will movetoward the axis of the center punch 4 simultaneously and equally so thatwhen the ends of the said levers 7 engage an obstruction, such as theperiphery of the shaft 18, the ends of all of the said levers 7 will beequidistant from the axis of the center punch 4.

It is also obvious that inasmuch as the face of the disk 2 is at rightangles to the longitudinal axis of the tubular member 1 and the centerpunch 4, slidably mounted therein, the said tubular member 1 and thecenter punch 4 may be easily alined with a shaft 18 by placing the outerface of the said disk 2 against the end of the said shaft 18 by movingthe handle 12, and the frustoconical portion 10 thereon, toward the saiddisk 2, the end of the said shaft 18 being also at right angles to thelongitudinal axis thereof, for the reason that such shafts are usuallyfaced by placing in a lathe in which the cutting tool, in cutting offthe said shaft, is moved inward on a line at right angles to the centerof the said shaft.

The operation is as follows:

In order to make an indenture in the exact center of a cylindrical shaft18 or the like, by placing the disk 2 against the end of the shaft 18 itis evident that as the said disk 2 is at direct right angles to thetubular member 1 that the center punch 4, being slidably mounted in thetubular member 1, will also be at right angles to the disk 2, andconsequently parallel with the shaft 18.

By moving the handle 12 upon the tubular member 1 against the tension ofthe spring 15 and in the direction of the disk Q, it is-evident that thefrustoconical portion 10 on the inner end of the said handle 12willengage the inner ends 9 of the levers 7 and move the said inner ends9 outward, and consequently the outer ends of the levers 7 will ybemoved toward each other an equal amount and against the tension of the'springs 20, which normally retain the outer ends of the levers 7 iin anopen position, until the said outer ends of the levers 7 engage theperiphery of theshaft 18.

'By striking a blow upon 'the end 22 of vthe center punch t with ahammer or 'similar device, it fisevident that'an indenture will be lmadelin the exact center of the shaft 18.

It is evident that the greater the force used on the handle 12 in movingthe same against the ends 9 of the levers 7 the greater will be theforce with which the said ends of'thesaid levers 7 will engage and holdonto 'the shaft 18. 1t Ais `also evident that the amount ofthe blowreceived on the end 22 of'the'center punch 4L will'be vreceived by theshaftflS yand will in no wisefbe imparted to thetubular member 1, forthe reason that the pins 5 in the said punch l1 will move in the slots 6toward the end ofthe tubular member 1, to whichthe disk 2 is secured.

The 'tool may be easily released by relieving the pressure'of the:handle 1Q, when the `spring 15 will move the said handle 12 and thevfrusto-coni`cal yportion 10 thereon away from the vends 9 of thellevers 7, when the springs 20 will move the ends of the levers 7outward within the radial slots 3 `of the disk 2 and away from the shaft18, thereby allowingthe tool *to be easily removed.

It is obvious from the foregoing that I have `provided improved meansfor automatically centering a center punch upon the endof a cylindricalsha-ft, and itis also evident that the automatic center punch 'is'adapted -to engag'evshafts of different diameter.

Having thus described my invention, what Iclaim as new and 'desire tosecure by L'et ters Patent 'is- 1. An automatic center punch comprising-aftubular member means secured to one end o'f the 'tubular member andadapted lto parallel ythe'same with ashaft to be centered; a centerpunch slidably mounted within the tubular member; llevers pivotallymounted upon the tubular member and adapted to engage the periphery of-a shaft; and means freely slidable upon the tubular vmemberandfad'apted to -move'the levers into engagement with the periphery of ashaft.

2.Y An automatic center punch comprising a 'tubular member; a disksecured at right Aably 'mounted within the tubular member;

levers pivotally mounted upon the tubular member and arranged to engagethe periphery of a shaft to be centered; and means slidably mounted uponthe tubular member and adapted to engage one end of each lever and tomove the opposite end thereof onto the periphery of ashaft tobe'centered.

3. An automatic center punchcomprising a 'tubular member; a diskVsecured a't right angles to one endof the tubular member; a centervpunch slidably mounted within the tubular member; and means operativelyconnected to the ytubular ymember yand adapted to aline the same withthe shaft, said 'means passing` through the disk and slidably engagedthereby.

11. An automatic center punch comprising a tubular member; a centerypunch slidably mounted within'the tubular member; means secured to oneend ofthe tubular member and adapted `to :parallel the same with a shaftto be centered; `levers pivotally mounted upon ythe tubular member I"andadapted to engage the periphery of a shaft 'to be centered; and meansfreely slidable upon the tubular member and adapted vitoenlgage one endof each lever and'cause theopposite end thereof 'to )engage theperiphery of the shaft and thereby aline the tubular member andcenterpunch therein with -the shaft, said leversextending through said `firstmentioned ymeans and vbeing braced thereby.

5. An automatic center punch comprising a tubular member; 'a vcenterrpunch slidably mounted within the tubular member; a disk having radialslots therein secured to one end of the tubular'member whereby the samemay be paralled with a shaft to be centered; levers pivotally mountedupon the tubular member and extending through the radial slots andarranged to engage the periphery of the shaft; and means slidablyymounted upon the tubular member and adapted 'to engage one end of eachllever and to cause the opposite ends of said levers to engage-theperiphery o'f the shaft to be vcentered 'and to laline the tubularmember and punch ytherein with said shaft.

6. An automatic center punch comprising, a tubular member; a centerslidably mounted within the tubular member; a disk having radial slotstherein securedfto one end of the tubular member and adapted to parallelthe same with a shaft to be centered; vlevers pivotally mounted upon thetubular member and having one end thereof extending through the slotsand arranged to engage the periphery of the shaft; and a handleslidvably mounted upon the tubular member and 130L having arusto-conieal portion adapted to nature in the presence of tWosubscribing engage one end offeaoh lever and cause the Witnesses.

other ends thereo extending through the v radial slots to engage theperiphery of the CHARLES L' THROCKMORTGN shaft and thereby aline thetubular member Witnesses:

and punch therein With said shaft.

In Witness whereof, I hereunto set my sig- PETER IvERsoN, W. N.BENEDICT.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents, Washington, D. p.

